Airway mucin hypersecretion is associated with a variety of diseases characterized by airway inflammation such as asthma, chronic bronchitis, and cystic fibrosis. In these disease states, excessive airway secretion is a cause of morbidity. Human airway epithelial cells express at least seven mucin genes. The relative contribution of each of these gene products to airway hypersecretion is unknown at present. To measure secreted products of individual genes in vitro and in airway secretions, we have produced fusion proteins containing unique nonglycosylated epitopes from mucin genes expressed in the airway. They are used to raise antisera specific for individual gene products. Creation of enzyme-linked immunoassays allows for the assay of mucin-gene-specific products in culture media from in vitro experiments or in airway secretions. In addition, plasmids with inserts containing unique DNA sequences of the mucin genes known to be expressed in human airway epithelial cells have been created to allow for the creation of riboprobes. These riboprobes will be used for the quantitative analysis of mucin gene mRNA in airway cells.